End-cell switch.



C. AMBRUSTER.

END CELL SWITCH.

APPLICATION FILED JUNE 30.1913.

1 01,424. Patented Oct. 17, 1916.

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WITNESSES INVE N TOR fornezz us' firn brusier B7 W @s W ATTORNEY.

UNITED STATES PATENT OFFICE.

CORNELIUS AMBRUSTER, 0F ROSLYN, PENNSYLVANIA.

END-CELL SWITCH.

To all whom it may concern Be it known that I, CORNELIUS AMBRUs- TER, a citizen of the United States, and a resident of Roslyn, county of Montgomery, State of Pennsylvania, have invented certain new and useful Improvements in End- Cell Switches, of which the following is a specification. I

My invention relates to multiple contact switches such as those used for cutting in and out the end cells of a storage battery, and its object is to provide means for reducing the sparking or arcing which sometimes takes place when the traveling brush of such a switch is moving from one point to the next. As it is well known such a cell switch is designed to permit the traveling brush topass from one point to the next without interrupting the circuit, and at the samev time without absolutely short-circuiting the cells connected between the two points.

However, when the brush is passing from one point to the next a local circuit is established between the two points which permits a very considerable fiow of current from the intervening cells, this current being limited by auxiliary contact resistances. In certain positions of the traveling brush this current is of considerable amount and as the brush moves this local current must finally be interrupted producing a tendency to excessive sparking or arcing, especially where two or three cells are connected between adjacent points. In order to eliminate this sparking I provide auxiliary contacts on either side of the traveling brush of non-fusing material and auxiliary contacts adjacent to the main contact points of the switch composed of high resistance laminations, together with blocks of lower resistance suitably disposed to accomplish the desired end as will be explained more fully below.

In the drawings Figure 1 is a plan view showing three consecutive points of an end cell swltch, the contact rail and traveling brush embodying features of my invention; Fig. 2 is an elevation'to an enlarged scale of the traveling brush and two of the switch points shown in Fig. 1, and Fig. 3 is an ele-.

vation similar to Fig. 2 showing the brush in another position.

In Fig. 1 R is the continuous contact rail and A A and A are three consecutive points of a cell switch connected to the battery cells D. B is the traveling brush. As here shown two cells of the battery are con- Specification of Letters Patent.

Patented Oct. 17, 1916.

Application filed June 30, 1913. Serial No. 776,600.

nected between points A and A and three cells between points A and A The arrangement of auxiliary contacts is more clearly shown in Fig. 2 in which the brush and two adjacent switch points are shown in elevation. The brush B is of copper or similar conducting metal and carries on either side trailers T and T of graphite or similar non-fusing material maintained in good electrical contact with the brush B. A and A are the main contacts ofadjacent points of the switch made of copper or similar conducting metal. On either side of each of these main contacts is a series of auxiliary contacts composed of sections or lami- -nations of different thickness and specific resistance. Immediately next to the metallic contacts A and A are blocks of graphite P and P of high specific resistance as compared with the metallic contact point and yet of considerably lower resistance than other portions of the auxiliary contacts. Next to the blocks P and 1 are a series of thinner laminations of carbon C and C The specific resistance of these laminations is considerably higher than that of the blocks P and P and the surface contact resistance between adjacent laminations is comparatively high. Outside of the laminations C and C are two graphite blocks S and S of lower specific resistance than the laminations C and C and of a width practically the same as that of the trailers T and T In Fig. 2 the traveling brush is assumed to be moved in the direction of the arrow and has arrived at an intermediate position between the two contacts such that trailer T is in contact with contact block S while the brush B is just about to break contact with the block S This is the critical position of the brush when moving in this direction when sparking is liable to occur. However, with the construction shown and the materials chosen as above described there is a comparatively good contact and low resistance in the circuit between brush B via trailer T to contact block S so that the current passing between the adjacent switch points through this path produces a very small drop of voltage between brush B and contact block S, and thus reduces the sparking to a negligible amount. The total drop in voltage between contact points A and A is, however, fixed by the voltage of the cells connected between these two points,

and in order to reduce the voltage drop between brush B and contact block S to a negligible amount, the total voltage between points A and A must be absorbed at some other point in the local circuit. This is accomplished by means of the high resistance laminations C the design being such that practically all of the voltage drop between A and A is absorbed in these laminations.

In other words, at the critical instant when the metallic portion of brush B is breaking contact with'block S there is a low resistance path around the point of rupture and a comparatively high resistance path in series therewith.

In Fig. 3 the brush is shown just midway between the two contacts. In this position the laminations C and C are practically short circuited, but at the same time there is no metallic circuit between the two points A and A and the local circuit between these two points is still of comparatively high resistance. The total current passing from the battery to the load circuit is divided, part of it passing from contact point A and part from contact A through blocks P and P and trailers T and T respectively to the brush B. It is important, therefore, that these two circuits should be of comparatively low resistance in order to provide for this outgoing circuit and the blocks P and P are, therefore, made of considerable thickness, and of lower specific resistance than the laminations C and C as shown and described above.

It will be noted that the laminated auxiliary contacts P 0 S S C and P constitute graduated resistances connected to ad jacent switch points, whereof a group P C and S is progressively cut out of circuit on one side ofthe brush, and a group S, C and P is similarly brought into circuit on the other side of the brush as the brush travels from one point to the next,

thus transferring the voltage drop between the two points from the auxiliary resistance on one side to that on the other without at any time concentrating this drop at the metallic contact surface of the brush.

Having thus described my invention what I claim and desire to secure by Letters Patent isv 1. In an end cell switch the combination of a fixed and a movable switch member, each havinglateral non-fusing contacts of comparatively low specific resistance, and a comparatively high resistance interposed between one of said members and its contact, substantially as described.

2. In an end cell switch the combination of metallic switch members arranged to slide out of contact to break a circuit, auxiliary non-fusing contacts laterally applied to said switch members, and adapted during the movement thereof to form a path of low resistance in multiple with the path of rupture formed between one of'the switch members and the auxiliary contact of the other to divert current .from such path of rupture,

- and a high resistance interposed between the last mentioned switch member and its auxiliary contact, and in series with said multiple paths to carry the diverted current and thus reduce the voltage and current across the point of rupture.

3. In an end cell switch the combination of a fixed and movable switch member each having lateral non-fusing contact of comparatively low specific resistance and surface contact laminations constituting a step by step high resistance interposed between one of said members and its contact.

In testimony whereof I have hereunto signed my name.

CORNELIUS AMBRUSTER.

Witnesses:

T. L. HAM ERSLEY, J. W. AOHARD. 

